The Photo sensory Receptors and Signal Transduction GRC meeting is the pre-eminent meeting in the field of the mechanistic basis and effects of photoreception. Having been established in 2000, the meeting alternates between US and European sites every two years, with the next meeting scheduled for April 18-23, 2010 at the Il Ciocco site used for three prior conferences. The photo sensor community encompasses a diverse variety of fields. For this reason, the primary objective of this meeting is to provide researchers studying the biological, chemical and physical aspects of light detection to share their newest data with each other rather than within more limited subcommunities. Aided by the explosion of newly-available photosensors provided by genomic sequencing efforts, this field has been joined by both new families of photoreceptors and a many new members of existing ones. Taken together, these provide a diverse group of systems to answer fundamental questions in protein signaling: How can small molecule chromophores trigger allosteric changes to surrounding proteins? How are these changes transmitted to downstream effectors? How are parameters of this process tuned to match the needs of the biological system? These questions are of central interest to human physiology (e.g. vision, circadian rhythms) and bacterial, plant and animal biology in general. Further, these are important to the development of novel biological research tools and general understanding of protein structure/function/regulation. The GRC meeting consists of both oral presentations and poster sessions. Oral presentations are organized in a conventional GRC format, with nine sessions over five days that facilitate comparative discussions of different families of photoreceptors. Presentations will be given by established investigators in the fields of biochemistry, biophysics, cell biology, chemistry, microbiology, physiology and plant biology, mixed with newcomers and early career scientists with exceptional new results. Sessions will be chaired by prominent and interactive researchers who bring their expertise to integrate results across speakers and in context of the major questions in the field. Complementing the oral presentations, poster sessions will provide opportunities for all attendees to present and discuss their findings with other members of the field. New to the 2010 meeting, we will add a Gordon Research Seminar organized and attended by, students and postdocs to give additional presentation and networking opportunities to this critical group of our community. PUBLIC HEALTH RELEVANCE: The Photo sensory Receptors and Signal Transduction GRC meeting provides a forum for researchers in the area of photoreception to meet and discuss issues of common interest in receptor mechanism. This field is extremely diverse, as the same principles of light detection are conserved widely across biology, and hence the need for a meeting which integrates this community. The issues discussed here are of central interest to human physiology (e.g. vision, circadian rhythms), the development of novel tools for biological research and general understanding of protein structure/function/regulation.